Episodic deformation and reactions in mylonitic high-grade metamorphic granulites from Dronning Maud Land, Antarctica ...

• Main Authors: Engvik, Ane K., Mertens, Cornelia, Trepmann, Claudia A.
• Format: Text
• Language: English
• Published: ETH Zurich 2020
• Subjects: Orthopyroxene; Granulite; Microfabric; Diffusional creep; Episodic deformation; Shear zone; Dronning Maud Land; Antarc*; Antarctica
• Online Access: https://dx.doi.org/10.3929/ethz-b-000444399; http://hdl.handle.net/20.500.11850/444399

Microfabrics of mylonitic orthopyroxene-bearing quartzofeldspatic granulites from central Dronning Maud Land, Antarctica, have been investigated to evaluate the deformation behaviour at lower crustal conditions. The microfabric is characterized by a fine-grained matrix of dispersed feldspar, quartz and orthopyroxene, which contains monophase elongate quartz and feldspar aggregates, so-called ribbons, and elongate monocrystalline orthopyroxene ribbon grains. The observed crystallographic preferred orientation (CPO) of orthopyroxene ribbon grains that contain clinopyroxene exsolution lamellae in (100) and kink bands in equidimensional porphyroclasts indicate (100)[001] dislocation glide. Fine-grained matrix orthopyroxene formed by deformation of porphyroclasts and growth in strain shadows during diffusional creep, indicating a separate stage of deformation and reaction. Although dislocation creep of coarse ribbon quartz is indicated by sutured grain boundaries at high angle to the ribbon boundary and few ... : Journal of Structural Geology, 141 ...